High fidelity—or hi-fi or hifi —reproduction is a term used by home stereo listeners and home audio enthusiasts (audiophiles) to refer to high-quality reproduction of sound[1] to distinguish it from the poorer quality sound produced by inexpensive audio equipment, or the inferior quality of sound reproduction characteristic of recordings made until the late 1940s. Ideally, high-fidelity equipment has minimal amounts of noise and distortion and an accurate frequency response.
One effort to standardize the term was the 1966 German Deutsches Institut für Normung (DIN) standard DIN 45500. DIN 45500 approval was intended to provide audio equipment buyers with reassurance that their equipment was capable of good quality reproduction. In theory, only stereo equipment that met the standard could bear the words 'Hi-Fi'. This standard was well intentioned but only mildly successful; in practice, the term was widely misapplied to audio products that did not remotely approach the DIN basis specifications.